I got same problem on my router. After investigating on this i found that the web server port of my router got changed. For me http://192.168.1.1:24576/ is working.
Usually when we write "192.168.1.1" browser understands it as "http://192.168.1.1:8080/" 80 is Web server or Hypertext Transfer Protocol daemon, port 80 is the port that the server "listens to" or expects to receive from a Web client, assuming that the default was taken when the server was configured or set up.
So the bug in router is changing Web server from 80 to some random number. In my case it was 24576. It might be a case of dead web server on router but this is very low.